Wireless Charging Shift Ahead

At least four different approaches to wireless charging are vying to power billions of next-generation mobile devices. Today only one has a beachhead in about a million systems: the Wireless Power Consortium's Qi inductive charging technology.

By 2018, analysts say, the race will be all but over with one player dominating the 700 million systems using wireless charging. Experts expect a technology shift to resonant charging after a generation of hybrid inductive/resonant products currently coming on the market. Before it's over, Apple is expected to debut what could be a wild-card proprietary approach.

Wireless charging "standards have to converge, and I think this year they will figure out this market is not taking off until they get together," Henry Samueli, the chairman and CTO of Broadcom, said at a company event in December in San Francisco. "It's about much more than a smartphone market. The main driver is the Internet of Things."

Ryan Sanderson, a wireless charging analyst at IHS, told us the mobile phone and tablet markets will be key to volume adoption of wireless charging in the coming years. IHS forecasts assume that at least one major cellphone manufacturer will integrate wireless power capability throughout its ecosystem by 2016.

"Apple is probably not eager to adopt another standard for it. They'll want to develop their own thing. They have a huge influence, along with Samsung," IHS analyst Jason dePreaux told us. "It will take those two companies to create a standard, not just saying the standard or joining an alliance, but actually building it in. It's several years away, though, especially on the Apple side."

Three types of main wireless charging technologies are contenders in the race to mainstream use -- magnetic induction, magnetic resonance, and niche solutions such as radio frequency. On the following pages, we will explore each in some detail. Though dePreaux said there isn't much difference in power or charging time among the technologies, an Ars Technica speed test of the Qi (pronounced chee) technology showed that charging a Google Nexus 7 wirelessly took nearly three times as long as using a power adapter.

Trade groups of chip makers and patent holders back different charging platforms. The Wireless Power Consortium (WPC) backs inductive and bridge solutions, while the Association for Wireless Power (A4WP) champions resonance. Seeing the writing on the wall, the Power Matters Alliance has moved to embrace resonant charging, as well.

The startup Humavox is going it alone with an approach that is based on what it calls radio frequency charging. Still, market watchers say other players and technologies could emerge before the dust clears.

"In the future, it's possible that technologies which offer the consumer even more freedom of space and distance to charge wirelessly -- RF perhaps being an example of this -- will enter the market and compete with resonant technologies," Sanderson said. Advancements are likely several years out. "In my opinion, it will be difficult for a new technology to enter the market once an infrastructure is in place, and therefore, if one technology is adopted in volume in the next two years, it is likely to remain the technology of choice for the future."

Last year, 20 million wireless charging receivers were shipped, and though most of them were inductive, Sanderson expects the market to grow to 700 million devices in four years. Inductive and resonant wireless chargers will ship in 2014, with resonant/bridge solutions expected to ramp up in the second half of the year.

A standard is "not taking up faster because folks are confused by the existence of what appears to be competing standards," John Perzow, the WPC's vice president of market development for Wireless Power Consortium, told us. "The well-known standards -- Power Matters Alliance, A4Wp, WPC -- those differentiating is making it hard for groups to combine… They don't share communication protocol. They won't talk to each other."

But consolidation is necessary before the technology can become ubiquitous. Only inductive and radio frequency products are available to the public, with Qi inductive technology built into products such as the Samsung Galaxy S4, Nokia Lumia 920, and Google Nexus phones and tablets. Major market players such as Broadcom, HTC, and Samsung are among the members of both industry groups.

My company has just finished developing a Qi based phone charger design for one of the world's largest car manufacturers.Having this built into production cars is bound to boost the Qi standard over any competing standard.

I would love to see some direct comparisons as well - I found very little data on power efficiency/time in my research. Seems to me that the next hurdle to overcome in charging will be getting the efficient power transfer of inductive with resonance's ease of placement.

There have been some very positive changes in charging with the standardization on microUSB as a common plug standard. Reading this article reminded me of the bad old days where each device needed a special cable. All that I see is a multiplicity of standards that will be going away within a couple of years. It does not make me want to commit, either as a device designer or a consumer.

Congrats on a well-researched and well-written overview article. A growing number of articles have tried to accomplish an overview of the wireless power standards development, and I find this to be the most accurate. This is speaking from 4+ years of experience as an antenna developer for wireless power devices.

To me, wireless charging provides the conveience with the price of low energy efficiency. The development is primarily focused on efficiency improvement. It is way better than the first generation inductive charging; yet, it can't be as good as direct contact simply by Law of Physics. Anyone can provide some measurement data of efficiency vs different method will help the community to understand. :)

The last point from Lachman I think nicely summarizes things. There is no one single magnetic standard and there will need to be more than one power source as well. A receiving system that can easily be integrated into a device based on that device's shape and size is also very important.

I think much of the "push" for wireless charging has to do with limited access to charging throughout the day and the constraints that are placed on mobility by the current system. It's troubling to see how as devices become more and more complex they continue to offer little in terms of power-saving and endurance. Performance is one thing, but devices need to be operational in order to accomplish what they are intended to accomplish. That isn't being done right now and so the demand for wireless charging is on the rise.

I can see that wireless charging is convienent since all you have to do is place your device on a mat and it will get chaged. Has there been any information about the efficiency of this system? I expect that it is very poor. With the push to save power and create new technologies that are more efficient, I don't understand the push for wireless charging. I will continue to plug in my devices even if it only saves me a few pennies.